The return of widespread sanctions against Iran's nuclear program "must not be the end of diplomacy" with Tehran, the European Union's top diplomat said on Sunday.
While the bloc will follow the United Nations in reimposing sanctions, "a sustainable solution to the Iranian nuclear issue can only be achieved through negotiations", Kaja Kallas said in a statement.
The UN reinstated an arms embargo and other sanctions on Iran on Saturday following a process triggered by key European powers that Tehran has warned will be met with a harsh response.
Britain, France and Germany triggered the return of sanctions on Iran at the UN Security Council over accusations the country has violated a 2015 deal that aimed to stop it developing a nuclear bomb. Iran denies seeking nuclear weapons.
The end of the decade-long nuclear deal originally agreed by Iran, Britain, Germany, France, the United States, Russia and China is likely to exacerbate tensions in the Middle East, just months after Israel and the US bombed Iranian nuclear sites.
UN sanctions imposed by the Security Council in resolutions adopted between 2006 and 2010 were reinstated at 8 p.m. EDT Saturday (0000 GMT).